Ignition-coil.



E. P. d: T. L. LEE.

IGNITION COIL.

APPLlcATIou min JULY 9.1911.

Patented Apr. 8,1919.

LVIIIAIIIIIIII lIIIIIIIIIIIIII UNITED STATES PATENT OFFICE EARLE P. LEEAND THOMAS L. LEE, OF ROCHESTER, NEW YORK, ASSIGNORS TO NORTH ELSTELECTRIC COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION 0F NEW YORK.

IGNITION-COIL.

Speccaton o1' Letters Patent.

Patented Apr. 8, 1919.

To all whom it may concern.'

Be it known that we, EARLE P. Lun and THOMAS L. LEE, citizens of theUnited States, residin at Rochester, in the county of Monroe an State ofNew York, have invented certain new and useful Improvements inIgnition-Coils; and we do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it ap ertains to make and use thesame.

his invention relates to an induction-coil suitable for use in producingthe high-tension discharge used for ignitlon in internalcombustionengines.

Coils for the purpose in question are usually made with long straightcores, having high reluctance, in order to secure a sufliciently rapidresponse to the very short periods of ener 'zation available withhighspeed multi-cy inder engines. Coils of this form are comparativelyineilicient, however, particularly at the lower engine-s eeds, and therequire primary windings o such low resistance that if such a coil besubjected steadily to an E. M. F. equal to that by which it isintermittently ener ized when in use, the coil will be damaged y heatingor the source of energy, if a battery, will be seriously depleted.

To secure a higher degree of efficiency than can be attained by astraight-core coil, it has been proposed to provide an ignitioncoil witha closed or substantially closed core aii'ordin a magnetic circuit oflow reluctance. uch an arrangement has never gone into successfulcommercial use in connection with high-speed apparatus, so far as thepresent inventors are informed, and this is apparently due to variousdefects, both constructional and electrical, of coils of this type, whenconstructed in accordance with the practice prevailing in themanufacture of analogous apparatus such as commercial transformers, inwhich the closed cores are built up of punchings or laminations of sheetiron. y

The objects of the present invention are to produce an ignition-coil ofthe compact, inexpensive, eilicient and reliable character necessary forsuccessful commercial use in connection with the engines ofmotor-vehicles, and to dispense with the necessity of resistance-devicesor automatic cut-outs for 56 the protection of the battery and the coilfrom an accidental closed circuit when the apparatus is not in use.

It has been found that the foregoing objects may be attained, in anignition-coil having a substantially closed magnetic circuit o lowreluctance, by a construction and arrangement of parts such as to avoidthe difficulties heretofore encountered in devices of this type, andarticularly by a form and arrangement of tlli) constructed partly orwholly of iron wire in place of the lamine@ previously used for similarapparatus.

Other features of the invention, conducing to the desired result, willbe set forth 1n the following description of a preferred embodiment ofthe invention.

In the accompanying drawings Figure 1 is a plan-view of an ignition-coilembodying the present invention; Fig. 2 is a side-elevation of the coil,with the casing and the terminal-insulators in section on the line 2-2in Fig. 1; Fig. 3 is a vertical section of the coil-proper and thecasing, on the line 3-3 in Fig. 1; and Fig. 4 is a detail-view, in plan,showin the relation of the tie-rod to the core-mem ers.

The invention is illustrated as embodied in an ignition-coil adapted foruse in connection with the multi-cylinder high-speed engine of amotor-vehicle. This coil has a substantially closed magnetic circuitproduced by the combination of two members which are hereinafterreferred to as the core and the yoke-member.

The core l() is composed of parallel iron wires arranged in the form ofa cylindrical bundle. The primary winding 11 is mounted upon andinsulated from this core in the usual manner, and the high-tensionsecondary winding 12 surrounds the primary winding and the core.

The yoke-member above referred to is in the form of a continuousapproximately rectangular ring, which constitutes, in effect, two yokesconnecting the opposite ends of the core 10. This yoke-member ispreferably formed of iron wire wound continuously on a suitable form,and at the corners of the yoke-member the turns of wire are heldsecurely in correct relation by sheetsmetal clips l having lugs 15 whichare bent around the edges of the core-member.

To prevent the discharge of high-tension current from the secondarywinding to the e core such that it may beV yoke-member, the ends of thewindings are covered by caps 16 of insulating-material.

The use of iron wire in place of lamina? of sheet-metal in the core andthe yoke-mem ber has been found to have important advantages, relatingboth to electrical eliciency and to economy and simplicity inmanufacture. A coil so constructed, when energized through acircuit-closer of the ordinary single-contact type, will give a spark ofapproximately constant length and intensity throughout a wide range ofspeeds.

In the matter of manufacture, the wire core has the important advantagethat it may be made circular in cross-section, so as to conform towindings of similar form, whichmay be produced more easily and cheaplythan windings of other forms, while requiring a minimum length of wirefor a given number of turns. The wire yokemember is also easily andcheaply constructed; and the use of an endless yoke-member incombination with a straight core permits the windings to be formedseparately, previous to the assembling of the core-members.

A feature of the invention resides in the simple and effective meansused to secure the members hereinbefore described together in theirproper relation, and to fix them in place in the casing which inclosesthem. For this purpose a tie-rod 17 is used, this rod passing through atube 18 embedded axially in the core 10. The tie-rod is passed throughthe upper and lower parts of the yoke-member 13, and it has been foundthat this may be done.` without seriously distorting the yoke-member, bymerely thrusting the rod between the turns of wire. The clips 14 preventthe wire from spreading to any undue extent, and the wire will crowdtogether, at either side of the tie-rod, so that little or no change inthe width and the thickness of the yoke-member is produced by theintroduction of the rod.

The ends of the tie-rod are threaded, and an oblong metal plate 19 isscrewed to the lower end. A metal disk 20 and a nut 2l are mounted onthe rod above the yokemember, and when the nut is screwed down the upperand lower parts of the yoke-member are drawn tightly, between the disk2() and the plate 19, toward the ends of the core 10.

The lower end of the core is held in firm engagement with theyoke-member by the means just described, so as to produce a joint of lowreluctance. Since the coil has been found to work better with a slightgap in the magnetic circuit, a spacingwasher 22 of insulating-materialis interposed between the yoke-member and the upper end of the core.

The coil-proper is inclosed within a cas in and since the closedmagnetic circuit su stantially eliminates magnetic leakage, it

has been found that this casing may be made of metal, and that it is notnecessary to slot the casing or adopt any other expedient to prevent theoccurrence of eddy currents. The casing may therefore be made ver sturdyand may be formed integrally witli the base or ilange by which it ismounted or supported, instead of being separatelyV formed as in theordinary spark-coil, where the casing must be made of insulatingInaterial.

The illustrated casin comprises a body 23 with an open top. 'Illiis bodyis cast integrally with a late or flange 24 which serves as means orsecuring the coil to a suitable support, such for example, as the casingof the ignition-timing mechanism. The top of the body 23 is closed by acover 26, upon which is seated a block 27 of insulating-material. Thetie-rod 17 passes through the bottom of the casing and is secured by anut `25, while the upper end of the rod passes through the cover 26 andthe block 27, and'a nut 29 is screwed upon it. When the nut 29 istightened against the block the block and the cover are clamped securelyin place.

The block 27 serves as a mounting for the binding-posts through whichconnections are made with the primary winding of the coil. These postscomprise metallic inserts 30 embedded in the insulating-material andperforated to receive the binding-screws by which the primaryterminal-wires 31 are secured. The cover 26 is perforated at two pointsto receive two depending portions 28 on the block, the inserts 30 beingcoaxial with these depending portions, which serve to prevent rotationof the block with relation to the cover. External connections may bemade with the inserts in a similar manner, and the block 27 isprovidedwith two upwardly projecting semi-circular Ishields 32, whichare oppositely disposed. This arrangement of the shields tends toprevent incorrect connections between external conductors and the coil,as such extern al conductors approaching the coil from oppositedirections cannot, owing to the shields, be attached to the wrongbindingposts.

The outer terminal 33 of the secondary winding is mounted on the perihery of the winding, as shown in Fig. 2. he casing 23 is provided with aneck 34 into which a lug 35 of insulating-material is screwed. ilhisplug carries a metallic insert 36 which constitutes a binding-post foran external hightension conductor. The usual nut 38 may be used forattaching such conductor. Connection is made between the terminal 33 andthe post 36 by means of a coiled spring 37 which lies loosely in asocket in the ost and presses against the face of the terminal.y

An important advantage of the present construction resides in theprovision which it aii'ords for carrying away heat enerated in theprimar winding of the coi In ignition-coils o ordinary form the heatgenerated, in case of an accidentally prolonged closure of the circuit,is so great as to be injurious to the insulation, so that it iscustomary to guard against such heating by the use of cut-outs orthermo-positive resistance-devices. In the present construction,however, the heat communicated to the core 10 from the primary windingfollows a continuous metallic conductive path, through the yoke-member13, the plate 19 and the tie-rod 17, to the bottom'of the cas? iiig, andsince this casing is also of metal, it a ords an effective radiator todissipate the heat so conducted to it. Accordingly, it has been foundunnecessary to use cut-outs or resistance-devices with the present coll,since it will sustain without injury a continuous iiow of current underthe full E. M. F. employed in the normal intermittent operation of thecoil.

The invention is not limited to the embodiment thereof hereinbeforedescribed and illustrated in the accompanying drawings, 'but it may beembodied in various other forms within the scope of the followingclaims.

The invention claimed is:

1. An induction coil having, in combination, a straight iron core;windings on said core; an endless yoke-member surrouding said core andmagnetically connecting the ends thereof, said yoke-member comprisingiron-wire coiled continuously; and clips embracing said wire at eachside of the portions adjacent the ends of said core.

2. An induction-coil having, in combination, a straight core of ironwires; windings on said core;and an endless iron yoke-member,structurally separate from the core, surrounding the core andmagnetically connecting the ends thereof, with one end of the core inclose metallic engagement with said member and the other end separatedfrom said member by an air-gap.

3. An induction-coil having, in combination, a straight core; windingsthereon; a yoke-member magnetically connectin the ends of said coreand atie-rod passing on tudinally through the core and throu h the adjacentportions of said yoke-mem er to secure the parts together.

4. An induction-coil having, in combination, a straight core; windingsthereon; a yoke-member magneticall connecting the ends of said core; acasing inclosing the parts before recited; and a tie-rod passing throughthe core and the adjacent parts of said yokemember and secured to saidcasing.

5. An induction coil having, in combination, a straight core of ironwires; windings thereon; an endless yoke-member magnetically connectingthe ends of said core and formed of iron wire coiled continuously; and atie-rod passing through said core longitudinally and through theadjacent parts of said yoke-member.

6. An induction coil having, in combination, a core, windings thereon; ayoke-member formed of substantially parallel strands of iron wire; andmeans, for securing said core and said yoke-member together, passinbetween adjacent strands of the wire whic constitutes the latter withoutseverance of said strands.

7. An induction coil having, in combination, a core, windings thereon; ayoke-member formed of substantially parallel strands of iron Wire;means, for securing said core and said yoke-member together, passinbetween adjacent strands of the wire w ich constitutes the latterwithout severance of said strands; and ineans embracing the yokememberon either side of the securing-means and holding the strands of wire inclose engagement with each other.

8. An induction-coil having, in combination, a straight core of ironwires; windings thereon; an endless yoke-member surrounding said coreand magnetically connecting the ends thereof, said member being formedof iron wire wound continuously; and a tie-rod extending longitudinallythrough the core and thrust through the core-member between adjacentstrands of the iron wire thereof.

9. An induction coil having, in combination, a straight iron core' anendless yoke member connecting the en s of the core and formed of ironwire wound continuously; windings on the core; a metal casing inclosingsaid core, yoke-member and windings; and means for pressing theyoke-member toward a wall of the casing to maintain a heatconductiveconnection between these parts.

10. An induction-coil having, in combination, a core; windings thereon;a casing provided with a removable metal head; a terminal-block seatedon said head; and a tie-rod 4passing through said terminal-block, headand core to secure all of these parts in place.

11. An induction coil with a casing having a removable metal headprovided with two adjacent o enings; in combination with a terminal-book seated on the outer surface of said head and provided with portionsdependin throu h said openin and with conductive inserts ocated in saide ending portions and accessible from bot inner and outer surfaces ofthe terminal-block.

EARLE P. LEE. THOMAS L. LEE.

